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SCHATZENERGYRESEARCHCENTER
Comparative Performance of Electrolysis Cell Stacks
at the HSU Hydrogen Fueling Station
Meg Harper
Schatz Energy Research CenterHumboldt State University
National Hydrogen Association Annual MeetingMay 4, 2010
© 2010 Schatz Energy Research Center
Chris CapuanoProton Energy Systems
Greg Chapman and Peter Lehman
Schatz Energy Research Center
Outline
• Introduction• Station Overview• New Cell Stack Specifications• Performance Improvements• Conclusions• Questions
Energy in
H2 out
The ExperimentCompare the performance of Proton’s Next Generation cell stack to the originally
installed stack
LHV of H2 ProducedEnergy Consumption of Electrolyzer
Efficiency =
HSU Hydrogen Fueling Station
• Northernmost and only rural station on California’s Hydrogen Highway
• Grand opening was September 4, 2008
SERC Director Peter Lehman cuts the ribbon opening HSU’s station as Congressman Mike Thompson, HSU President Rollin Richmond and SERC engineer and project manager Greg Chapman look on.
Fueling Station & Fleet
Serves two vehicles:• Hydrogen-powered Toyota Prius• Toyota’s Fuel Cell Hybrid Vehicle (FCHV-adv)
Interpretive Sign
The station generates H2 with a Proton electrolyzer, compresses it to 420 bar storage with a PDC compressor, and dispenses it to vehicles at 350 bar with an FTI dispenser.
Electrolyzer
• Proton Systems HOGEN S40 PEM electrolyzer
• 2.3 kg H2 per day
• 99.9995% pure hydrogen
• H2 tested by Atlantic Analytical Lab and found to have no detectable impurities and be suitable for fuel cell vehicles
• 200 psig maximum output pressure
Data Acquisition and Instrumentation
DAQ recorded:• Power to the electrolyzer • Mass flow of hydrogen from the electrolyzer
Manually recorded:• Cell Stack Current using a current shunt attached to a Fluke 73 III multi-meter
• Cell Stack Voltage using a Fluke 45 multi-meter• Cell Stack temperature as measured by the unit’s thermistor in the water circulation system
Hydrogen Water Separator Tank
Hydrogen Gas Dryer
Heat Exchanger Bypass
• Adjustable valves allow water to partially bypass the heat exchanger to control the operating temperature of the cell stack
• System can run at temperatures up to 60 ˚C
• Testing occurred at 34 ˚C and 56 ˚C
Next Generation Cell Stack
• Proton Energy Systems developmental model
• Bipolar plate design which replaces frame, flow-field, and separator plate with a single component
• Reduction from 29 parts to 9 parts per stack
Experimental Results
Results of Cell Stack Performance Tests
Cell Stack
Temp (˚C)
Power (W)
Specific Energy
Consumption (kWh/kg H2)
Efficiency (%)
% Improvement
in Efficiency
Original 34.0 6067 57.3 58.3
New 33.9 5614 53.0 63.9 8.0%
Original 56.8 5620 53.1 62.9
New 56.6 5288 49.9 66.9 6.4%
LHV of H2 ProducedEnergy Consumption of Cell Stack
Efficiency =
Power Use
Error bars = 95% Confidence Interval
Overall Electrolyzer Energy Consumption
MeasuredOriginal(Low Temp)
Measured New (High Temp)
78 kWh/kg 70 kWh/kg
This is a comparison of overall energy consumption of the electrolyzer using the original cell stack operating at normal temperatures to the new cell stack operating at elevated temperatures. The energy use is shown for a measured H2 production rate of 18.0 slm.
Conclusions• The new cell stack is more efficient, improving by
approximately 8.0% at low temperatures and 6.4% at high temperatures.
• Using the new stack at higher temperatures decreases the overall electrolyzer energy consumption by 10%. This still represents a specific energy density of 70 kWh/kg, highlighting the need to improve the entire electrolyzer system.
• The new stack has worked well for three months.• If the HOGEN ran continuously, these efficiency
improvements would save us approximately $800/year in electricity costs. At a larger station these savings would be more substantial.
Many Thanks to Proton Energy Systems and Our
Original Project Sponsors:
Chevron Technology Ventures CalTrans
California Air Resources Board North Coast Unified Air Quality Management
District O&M Industries
HSU
Contact InformationSchatz Energy Research
CenterHumboldt State University
(707) [email protected]
Thank you
SCHATZENERGYRESEARCHCENTER Extra Slides for fielding
questions
Hydrogen Water
Separator
Hydrogen Gas Dryer
Measured Hydrogen Output
Hydrogen Water
Separator
Hydrogen Gas Dryer
More Hydrogen Output
Hydrogen Water
Separator
Hydrogen Gas Dryer
Less Hydrogen Output
SCHATZENERGYRESEARCHCENTER
Major Equipment Costs
Equipment Cost (USD)
Electrolyzer $76,600
Compressor $46,600
Storage Tanks $45,100
Dispenser $62,500
Taxes and Shipping
$22,200
Total $253,000
SCHATZENERGYRESEARCHCENTER
Total Station Cost
The total cost does not include the cost of 1300 ft2 of land donated by HSU.
Category Cost (USD)Major Equipment $253,000Balance of System $133,000Labor $220,000Indirect Costs $72,000Total $678,000
SCHATZENERGYRESEARCHCENTER
Interpretive Signs
The station has interpretive signage to inform visitors about what we’re doing, why we’re doing it, and how the station works.
SCHATZENERGYRESEARCHCENTER Compressor
• PDC single stage diaphragm compressor
• 6000 psig maximum discharge pressure
SCHATZENERGYRESEARCHCENTER
• Two 6000 psig ASME hydrogen storage tanks with a total capacity of 12 kg
• 30 gallon ballast tank between electrolyzer and compressor
Storage Tanks
SCHATZENERGYRESEARCHCENTER Dispenser
• FTI single hose dispenser• 5000 psig fill pressure• California Fuel Cell Partnership (CaFCP) fueling protocol and data support
